This invention relates generally to earth moving and shaping equipment and more particularly relates to a machine that restores a sunken roadway shoulder to the level of a roadway edge and provides a downward grade for rainwater drainage away from the roadway using only pre-existing shoulder material that is lying in place in a depressed and deteriorated shoulder at the time of the restoration.
Roadways are constructed of a relatively hard material for supporting vehicle traffic. They are typically constructed of pavement, such as asphalt or concrete, or of gravel that has been compacted from years of use to create a hard, smooth and relatively permanent path that resists erosion and softening from rain water. Most roadways also have parallel shoulders running along and adjacent both sides of the roadway and interposed between the roadway itself and a ditch and/or grass along the outer sides of the right-of-way. The shoulders provide strips that border the roadway in order to support vehicle wheels that stray off the roadway as a result of driver inattention, distraction, the need to pass oppositely moving traffic on a narrow roadway or for other reasons. The shoulders of most local, township, county and some state roads are composed of gravel, dirt or, most commonly, an aggregate mixture of both because these materials are less costly than roadway materials.
Because vehicle wheels occasionally stray from the roadway onto the shoulder, it is desirable that the shoulder that is adjacent the roadway meets the roadway at the same level as the pavement or gravel roadway. That allows a smooth transition between the roadway and the shoulder and avoids a ridge at the edge of the roadway that can deflect the steering of the vehicle and resist the return of vehicle wheels to the roadway. Roadways are also contoured with a central crown to enhance water drainage from the roadway. Desirably, the shoulder smoothly continues the downward grade away from the roadway in order to permit water drainage from the roadway to pass across the shoulder.
Unfortunately, over a period of time the level of the shoulder descends below the level of the edge of the roadway as a result of compression and outward displacement of shoulder materials resulting from the weight of vehicle wheels running off the road and from outward erosion of the shoulder material caused by rain water drainage from the roadway. This displacement and compression of the shoulder material leaves an undesirable and potentially hazardous ridge along the edge of the roadway. Similarly, when a roadway is replaced with new pavement, the edge of the new pavement may be at a higher level than the dirt and gravel adjacent to the roadway leaving the same kind of ridge.
The development of such roadway edge ridges requires maintenance by highway crews of the responsible governmental agency. The maintenance is conventionally accomplished by depositing new shoulder material, typically gravel, adjacent the roadway. This conventional maintenance requires the expense of new gravel and a labor intensive effort to position the new gravel in place and to level and grade the new gravel so that it has the desirable shoulder grade and level describe above. Typically, this maintenance is accomplished by slowly driving a gravel filled dump truck along the roadway. A chute that extends sideward from the truck cargo bed allows the new gravel to flow onto the shoulder. Workmen then walk along and shovel, rake and/or hoe the gravel into the desired grade and level. Because the gravel falls from the chute or is shoveled onto the shoulder in an uneven distribution and height, the process of properly contouring the gravel is labor intensive work. Often this manual contouring of the new gravel results in a transition with the roadway in which the level of the gravel varies between too high and too low. Additionally, the manual operation commonly leaves a considerable quantity of gravel lying on the roadway surface along its edge. As a result, a workman with a broom must follow along and sweep the gravel material outward from the roadway onto the shoulder. It is not unusual for this conventional maintenance operation to require four or more workers who move at a relatively slow pace along the roadway.
Therefore, there is a need for a machine that eliminates the need for the addition of new gravel, that reduces the number of required workers in order to reduce the cost of this maintenance, that speeds up the maintenance process, that improves the quality of the grading and level of the restored shoulder, that allows adjustment of the level and grade of the restored shoulder and that allows adjustable control of the level of the shoulder at its interface with the roadway. The present invention accomplishes all of those advantages. With the present invention, a single operator in one pass along the roadway recycles shoulder material that is already located in its displaced locations along the roadway and leaves a strip of loosened material having a predetermined and controllable thickness and contour with only very minor spillage onto the hard roadway. The single pass of the machine of the invention also leaves the loosened and recycled material at a uniform and controllably adjustable height above the edge of the pavement. That controllable height permits the loosened material along the shoulder to be compressed by simply driving the tires of a dump truck, preferably loaded for additional weight, along the recycled shoulder material to compress it to the level of the roadway edge to restore the shoulder to the desirable shoulder level and grade.